Enable middle button drag (libinput)

dummy@example.com (martin.hodges@getmail.no) — Mon, 25 Jan 2021 11:46:16 +0000

After a deal of de-bugging I have middle button drag on the Trackpoint middle button AND vertical scrolling on the Touchpad on my laptop. This is not simple.
1) libinput can only use udev found devices and does not seem to play nicely with other xorg pointer drivers.
2) libinput uses the same parameters by default for all mouse devices.
3) driver parameters my be placed in *.conf files in /etc/X11/xorg.conf.d/.

I have a file: 40-libinput.conf

Section "InputClass"
Identifier "Touchpad"
MatchDriver "libinput"
MatchIsTouchpad "on"
Option "Tapping" "on"
Option "ButtonMapping" "1 0 3"
Option "ScrollMethod" "edge"
EndSection

Section "Inputclass"
Identifier "Trackpoint"
MatchDriver "libinput"
MatchIsTouchpad "off"
Option "ScrollMethod" "none"
EndSection

The key to this is the MatchIsTouchpad lines which differentiate parameters between mouse types.
The Tapping "on" is my preference.
The ButtonMapping is to disable chord emulation of middle button on the TrackPad. Again, my preference

The key to getting middle mouse drag is by disabling the ScrollMethod. The default uses middle button hold to convert mouse movement to scroll events.

Dev1 Galaxy Forum / Enable middle button drag (libinput)

Enable middle button drag (libinput)